Many neurological diseases are progressive and may result in a wide range of symptoms such as weakness in the extremities, slurring of speech, vision abnormalities, difficulty breathing, difficulty swallowing, dementia, impaired balance, loss of memory, unsteady gait, muscle twitching, depression, anxiety, and mood swings. Some of these diseases are inherited, but the etiology of many cases is unknown. Indeed, the basis for many of these diseases may be due to environmental, toxic, or viral factors, as well as genetic predisposition, or a combination thereof. A GGGGCC repeat expansion ((GGGGCC)n) in C9ORF72 is a cause of neurological diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD), accounting for about 10% of each worldwide. There is no cure for many neurological diseases and treatment options are limited, thus there is a need in the art for methods of treating the diseases.